The invention relates to a vehicle with a power distributor and a control unit, wherein the power distributor comprises a bistable relay with at least one coil.
The electrical system of a vehicle has a number of consumer lines, which are supplied with electricity by means of a power distributor. At the same time the individual lines can be disconnected from and re-connected again to the vehicle electrical system by means of a relay. For example, when the vehicle is in a sleep mode, the individual consumer branches are disconnected from the vehicle electrical system, in order to reduce the static current consumption of the vehicle. When the vehicle is awoken, the consumer branches are re-connected again. According to the state of the art, monostable relays, which are switched with a control unit, are usually used for this purpose. Preferably these relays can be inserted, comparable to fuses in a fuse box, into the recesses, which are intended for the relays, in the power distributor. This arrangement makes it easy to access the defective relays and to replace them with unerring certainty.
The German Patent document DE 102 43 970 A1 describes bistable relays that are also used to switch consumer lines in the motor vehicle. In addition, the lines can be monitored at least to some extent with a microcomputer.
The object of the present invention is to provide an improved vehicle with a power distributor and a control unit, wherein the power distributor comprises a bistable relay with at least one coil.
According to the invention, the bistable relay, which can be set to a first switching state and a second switching state, has an integrated circuit, which activates the control unit by way of a control line. In this case the control unit defines one of two switching states by way of a control signal, in that the control unit applies a first control voltage or a second control voltage to the control line. In this context, the first control voltage corresponds to the first switching state, and the second control voltage corresponds to the second switching state. The integrated circuit switches a current pulse through the coil, in order to set the bistable relay to the switching state defined by the control unit.
This feature offers the advantage that the bistable relay is switched over by the integrated circuit, because the coil is supplied by the integrated circuit with the current pulse required to switch over the relay. The control unit is connected to the relay only by way of the control line. The control unit defines the switching state, to which the relay is to be set, over the control line. This arrangement offers the advantage that only one cable strand has to be run from the control unit to the bistable relay in the vehicle. The bistable relay with the integrated circuit can also be referred to as an intelligent relay.
According to a preferred embodiment of the present invention, the integrated circuit determines the switching state of the relay and compares the switching state of the relay with the defined switching state of the control unit. In the event that the determined switching state deviates from the defined switching state, the integrated circuit switches a current pulse through the coil, in order to set the bistable relay to the switching state defined by the control unit.
This approach guarantees that in an undefined switching state or a switching state, which does not correspond to the defined switching state, the relay is set to the defined switching state. A bistable relay can be set to an undefined switching state, when, for example, the relay is subject to a significant mechanical action, such as during a vehicle crash. The automatic resetting of a relay is common typically only in monostable relays that are permanently energized.
Preferably the integrated circuit includes a bridge circuit consisting of four self-blocking n-channel MOSFETs and a logic module. The logic module controls the gate electrodes of the MOSFETs as a function of the control signal of the control unit, in order to switch a current pulse through the coil and to set to the defined switching state.
The use of MOSFETs and the logic module enables the conversion of the integrated circuit as an application specific integrated circuit (ASIC) that is inexpensive and reliable and saves space.
According to an additional variant of the invention, the vehicle has a voltage source, with which the integrated circuit can be supplied with electric voltage at an operating voltage input of the integrated circuit. As a result, the supply of the ASIC with operating voltage is guaranteed. The operating voltage feeds the logic module with electric power and acts as the drain/source voltage of the MOSFETs of the bridge circuit.
In addition, the integrated circuit can also have a redundant voltage supply, so that when the voltage supply at the operating voltage input fails, the integrated circuit can be supplied with electric voltage by the control unit by way of the selection line. This feature offers the advantage that the integrated circuit can be supplied with operating voltage when, for example, an error occurs at the operating voltage input or in the event of a defective in-feed to the voltage source.
Furthermore, it is preferred that the integrated circuit has a control line input and that the control line is connected to the input by way of a plug and socket connection. A first current sink can be downstream of the input of the control line; and a contact cleaning current is adjustable by means of this first current sink by way of the control line.
A contact cleaning current reliably ensures that the integrated circuit stays permanently controllable with the relay. The contact cleaning current prevents the formation of contact resistances at the plug and socket connection.
According to a further development of the present invention, a second current sink is connected in parallel to the first current sink; and a status current is adjustable by the second current sink by way of the control line. The setting of the status current can be controlled by a pulse width modulated signal of the logical module to the second current sink; and the pulse width modulated status current can be determined by the control unit with a current mirror circuit. The data can be stored, as a function of the pulse width of the status current, in the logic module and in the control unit.
This arrangement allows stored data to be transmitted from the integrated circuit to the control unit by way of the pulse width modulation of the status current. This stored data can be, for example, the switching state of the relay or the status or diagnostic data of the relay (for example, “coil malfunction”), data regarding the operating voltage supply of the ASIC (for example, “low supply voltage, test supply”) or regarding the logic module (for example, “module defective, replace relay”); the range of data that can be determined depends on the range of functions of the ASIC.
According to a preferred embodiment of the invention, the integrated circuit has a reverse polarity protection function, which opens or closes the relay when an external voltage source is connected with reverse polarity.
There is a case of reverse polarity, when an external voltage source is brought with its higher potential to the vehicle body and with its lower potential to the plus (positive) pole or the remote start polarity of the vehicle. The integrated circuit has a reverse polarity protection circuit, which on the basis of the potential difference in the reverse polarity case and in a defined switching state allows a current flow in the coil in a direction defined by the reverse polarity protection circuit, in order to bring the relay into a different switching state.
For example, the vehicle can be a motor vehicle, a hybrid vehicle or an electric vehicle, which has at least one bistable relay. In this context at least one bistable relay includes an integrated circuit; the power distributor has a plug-in space, in order to integrate at least one bistable relay with an integrated circuit.
The plug-in space has all of the necessary contacts for the intelligent relay. If there are a plurality of intelligent relays, which can be integrated into a power distributor by way of a plug-in space, then the plug-in spaces can be arranged side by side. This arrangement allows a defective relay to be identified with unerring certainty and promptly replaced.
The invention is based on the following presented considerations.
Bistable relays are used in power distributors of motor vehicles or electric vehicles, in order to supply power to the electric consumers. The relays are plugged preferably into power distributor boxes. Soldered, force fitted or welded relays are also used. The current trend in modern vehicles is to use bistable relays in order to reduce, in particular, the power consumption when the vehicle is in running mode and in the immobilization mode. In the case of motor vehicles this strategy reduces the consumption of fuel; in electric vehicles it is possible to gain an extended cruising range.
However, a bistable relay has to be activated by use of an H-bridge circuit, in order to generate current pulses or current surges through the coil of the relay in both directions of current. The bridge circuit is usually a component of a control unit, so that not only the costs for the bridge circuit, but also two lines in the cable harness have to be provided; and these two lines run from the control unit to the bistable relay.
It can be proposed as an improvement, to integrate an electronic package in the form of a printed circuit board with an ASIC (application specific integrated circuit) into the relay. The integrated circuit of the ASIC is provided with operating voltage by way of the control unit or by way of the vehicle electrical system. The pulse selection of the coil by use of current pulses is also carried out by the integrated circuit, wherein the power required for the current pulses also comes from the electrical system of the vehicle.
Since a portion of the vehicle electrical system forms the closed loop control circuit, it is possible to dispense with a cable strand in the vehicle. In stark contrast to the conventional bistable relay, only one selection line runs from the control unit to the bistable relay.
In addition, the switching state of the bistable relay can be diagnosed by use of the integrated circuit. If, for example, in the event of a crash, the bistable relay does not occupy a defined switching position, then this situation is recognized by the integrated circuit; and a current pulse for switching over the relay is emitted.
Thus, the switching over of the relay can be induced by the control unit by way of the control line or by the relay's own diagnosis. This feature enables the use of bistable relays in safety relevant systems and eliminates the need to use permanently energized monostable relays.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.